In recent years, imaging apparatuses, such as digital cameras that convert an image signal obtained by an image sensor, such as a charge coupled device (CCD) image sensor, and record the converted signal in an embedded memory or a recording medium, have been widely used (for example, see Japanese Laid-open Patent Publication No. 2001-24928 and Japanese Laid-open Patent Publication No. 2008-11224). In such an imaging apparatus, when recording in a recording medium or the like is performed, image data of one frame having a plurality of pixels is encoded in the Joint Photographic Experts Group (JPEG) format to minimize the size of the image data and is then recorded.
The imaging apparatus includes an image processing apparatus having a function to clip a partial region in the image data of one frame and perform various imaging processing such as a magnification processing on the clipped image data (partial image data).
FIG. 9 illustrates a schematic view of a flow in a magnification processing method performed on partial image data in a known image processing apparatus. As illustrated in FIG. 9, a central processing unit (CPU) 61 analyzes header information stored in a memory 63 formed by a Synchronous Dynamic Random Access Memory (SDRAM), or the like, and added to the encoded data ED, and acquires a decoded image size. The CPU 61 secures a memory region necessary to extract image data that has the acquired image size in the memory 63. Then, a decoding unit 64 reads the encoded data ED from the memory 63, decodes the encoded data ED, and sequentially writes the decoded image data (decoded data DD) in the secured memory region.
Meanwhile, operation information including a clipping position and a magnification rate of the partial image data, or the like, is inputted from an input unit 62 into the CPU 61. The CPU 61 sets the clipping position and the magnification rate of the partial image data for a magnification processing unit 65. The magnification processing unit 65, on the basis of the settings set by the CPU 61, reads decoded data (partial image data PD) of the partial region to be magnified in the decoded data DD of the one frame stored in the memory 63. Then, the magnification processing unit 65 magnifies the read partial image data PD according to the magnification rate. Further, the magnification processing unit 65 stores the magnified partial image data (magnified image data MD) in the memory 63. The magnified image data MD stored in the memory 63 in such a way is displayed on a display unit, for example, a liquid crystal display (LCD), or recorded as a separate file in a recording medium.
However, in the known image processing apparatus (method), as illustrated in FIG. 9, the magnification processing is performed on the partial image data PD. Accordingly, it is necessary to provide a large-capacity memory region for storing the encoded data ED of at least one frame, the decoded data DD of one frame, and the magnified image data MD. Especially, when the image data is encoded in a variable length coding format such as the JPEG format, it is not possible to clip the image data of a region if the all of the encoded data ED of one frame is not decoded. Accordingly, it is necessary to provide a large-capacity memory for storing the decoded data DD of one frame.
However, in recent years, functions of such an imaging apparatus have become highly sophisticated due to an increasing number of pixels and increasing image quality and the installation of continuous shooting functions or the like. With the increasing number of pixels, the increasing image quality, and the sophisticated functions, the data amount to be processed by the image processing apparatus is increased. Accordingly, the capacity of the memory 63 necessary for the image processing is also increased. However, with the desire to reduce the size and cost of an imaging apparatus, generally, the capacity (for example, a memory capacity necessary for implementing the above-described magnification processing) of the memory 63 is small. Accordingly, especially in such an imaging apparatus, if a large capacity memory is used in implementing the imaging processing as described above, the number of files extendable in the memory 63 is limited. Accordingly, the amount of processing that can be concurrently implemented is also limited, and overall processing time necessary for the image processing is also increased.
Further, not only in the case where the magnification processing is performed on the partial image data PD, but also the large memory capacity is necessary in a case where an image processing other than the magnification processing is performed on the partial image data PD. Further, the problem of the increasing processing time often occurs when only a small capacity memory is provided. In addition, the problem also occurs even if a large capacity memory is provided.